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What Causes Labor to Begin?
For all the technology and advances we have made in modern medicine, we still don't know what triggers the onset of labor. Many patients have tried home remedies, eating Chinese or Mexican food, walking, walking and more walking, and making love. Sorry to say, to date none of these has been proven effective.

What we do know is that labor involves a very intricate relationship between the baby, the uterus and the placenta. Studies have shown that when the uterus reaches 40 weeks' size, it is more likely to trigger labor. This may be one reason twins tend to deliver early. The placenta has also been linked to labor initiation through cases where it lacks a certain chemical secretion. In those cases, the woman doesn't go into labor and must be induced. And babies suffering from severe neurological problems also need to be induced, suggesting the baby has a say in the beginning of labor.

Before we begin a discussion on labor, I must tell you that it's important for you to have a chat with your practitioner if you haven't done this already. During this discussion, you should establish when to call your doctor. You should also determine how long it's going to take to get to the hospital, and know exactly where Labor and Delivery is located.

Taking a step back, I want to remind you that labor can last a few hours or a few days! So don't go crazy when you feel the first contractions. There is ample time to observe what is going on. Many patients have some warning that labor is eminent. You may pass a bloody, mucus discharge – called the bloody show – several days in advance of labor. Or you may notice an increase in uterine tightness and cramping with intermittent sharp pains. As long as you're at or near your due date, I consider these to be the warm-up signs and not worthy of a call to the doctor in most cases.

It's common for first-time mothers, in particular, to worry they won't be able to recognize true labor. I smile, knowing the answer is usually quite apparent. Labor contractions are sharp, crampy pains that start slowly and increase in frequency and intensity over several hours. They tend to start in the back or top of the uterus and wrap around to the front, making the uterus firm all over. Contractions that last for 30-60 seconds, take your breath away and come back in another 4 to 6 minutes, with an increase in vaginal discharge, are signs that you are in labor. Other moms wonder if they will be able to determine when their water has broken. A sudden gush of warm fluid is the standard description of the amniotic sac breaking, but it can also be a slow, intermittent trickling of fluid. This may happen even without contractions. Now is a good time to call your doctor.

Some of my patients are hesitant to make that call. They aren't sure if what they're experiencing is really labor and don't want to head to the hospital only to be sent home in false labor. It is a good idea to wait until the contractions have been coming frequently for several hours and increasing in intensity before calling. But in the end you should err on the side of caution and make a phone call if you aren't sure. Let the professional give you guidance. And don't worry … we have a hard time figuring it out sometimes, too. When I'm not sure if a patient is in true labor, I find it useful to ask her if the baby is moving. In real labor, I find that the baby reduces its movement pattern considerably.

Labor is the culmination of your pregnancy, the last hurdle to overcome. The long months of waiting are over and parenthood awaits you and your partner. Remember that your obstetrician, family physician, nurse midwife, etc., understands what you are preparing to do and are here to help make the end of this journey a safe experience for you and your child.
Dr. Bettye M. Caldwell Ph.D. Professor of Pediatrics in Child Development and Education